This application requests a supplement to a current study, Physical Activity in Preschool Children (R01HD043126). The purpose of the ongoing study is to describe the physical activity behaviors of children in preschools and to identify environmental factors and institutional policies and practices that influence physical activity of children in preschools. As part of the ongoing study the investigators have developed a direct observation system for measuring physical activity and environmental influences on physical activity in 3 to 5 year-old children while they are in a preschool setting. The activities proposed in this supplement application would extend and expand the ongoing work. The specific aims of the supplement study are 1) to develop a system for direct observation of physical activity and potentially related physical and social environmental factors in young children in the home setting, and 2) to develop a system for direct observation of physical activity and potentially related physical and social environmental factors in children in the elementary school setting. The investigators will follow a nine-step process in developing each of the two new systems, beginning with the home system. The steps will include: research the relevant published literature, conduct environmental scans (preliminary observations) in 16 broadly representative settings (i.e., 16 homes or 16 elementary schools), develop a draft version of the system, create software for administering the system using hand-held computers, train research assistants to administer the system, conduct field testing in representative settings, analyze pilot data, review all pilot data and other pertinent information and modify the system as needed, and develop final software and detailed procedures manual. The two new systems, when combined with the system developed in the ongoing study, will provide researchers with state-of-the-art instruments for comprehensive examination of physical activity and the environmental factors that influence physical activity in children ages 3-11. [unreadable] [unreadable]